The present invention is directed to bicycles and, more particularly, to a low profile rear derailleur used to switch a chain among a plurality of sprockets that rotate with the rear wheel.
A bicycle rear derailleur is used to selectively engage a chain with one of a plurality of sprockets that rotate with the rear wheel of the bicycle. A typical rear derailleur comprises a base member, a movable member supporting a chain guide, and a linking mechanism coupled between the base member and the movable member so that the chain guide moves laterally relative to the base member. The base member usually is mounted to the rear end of the bicycle frame by a mounting bolt that screws into a threaded opening formed in the frame. Because of the nature of the lateral movement of the chain guide required to switch the chain among the sprockets, the linking mechanism, the movable member and the chain guide all protrude laterally outward by a significant distance, especially when the chain is engaged with the laterally outermost rear sprocket. As a result, the chain guide is susceptible to striking or becoming entangled with nearby objects, especially when riding off-road in mountainous terrain. The effect becomes more severe as the number of sprockets increase.